Intravenous administration equipment



Feb. 20, 1962 G. K. BURKE 3,021,841

INTRAVENOUS ADMINISTRATION EQUIPMENT Filed March 14, 1957 FIG. I

22 FIG.

63 INVENTOR GEORGE K. BURKE ATTORNEY United States Patent Ofiice3,921,841 Patented Feb. 20, 1962 3,021,841 INTRAVENOUS ADMlNISTRATIONEQUIPMENT George K. Burke, Bethichem, Pa., assignor, by mesneassignments, to Baxter Laboratories, Inc., Morton Grove, IiL, acorporation of Delaware Filed Mar. 14, 1957, Ser. No. 646,088 in Claims.(Cl. 128--214} This invention relates to venoclysis equipment, and moreparticularly to an improved device, for use in intravenousadministration, for the injection of fluid alternatively underconditions of gravity flow or forced injection.

In the administration of injection fluids, such as plasma or plasmasubstitutes, the fluid is caused to flow into the vein at acomparatively slow but steady rate. However, in cases of emergency itmay be necessary to force copious quantities of the fiuid into the veinin a short period of time. Accordingly, it is advantageous to provide asingle intravenous administration apparatus which is adapted to effect agravity flow of the injection fluid, under normal conditions, whilebeing further adapted to effect the forced injection of predeterminedquantities of the fluid when necessary or desirable. One form ofapparatus which may be advantageously'utilized for this purpose isdescribed and claimed in my co-pending application Serial No. 394,681,filed November 27, 1953, now Patent 2,967,325 issued October 6, 1959,for Venoclysis Equipment. The present invention relates to specificstructural improvements in the apparatus of the co-pending application,to the end that the apparatus may be utilized with greater efliciencyand with improved effectiveness.

In general, the intravenous administration equipment of the typeconcerned herein includes a hypodermic cannula, adapted for insertion inthe vein of a patient, and

communicating at one end with a length of flexible tubing. Connected inseries relation with the cannula and tubing are a manually operabledisplacement pump, a drip through the drip observation chamber, pump,tubing and cannula into the vein. The rate of fluid flow may becontrolled by means of an adjustable clamping device applied to thetubing, above the hypodermic cannula, and, advantageously, the rate offlow may be observed from the drip observation chamber, which isarranged so that the injection fluid enters the chamber in discretedroplets of as certainable volume, the flow of droplets being observablethrough a transparent outer housing of the drip observation chamber.

Under emergency conditions, it may be necessary to force blood into thevein at a rate greater than that possible through normal gravity flow,and, for this purpose the displacement pump may be actuated manually,advantageously by squeezing with the hand, to rapidly forcepredetermined quantities of injection fluid into the vein.

Ideally, the actuation of the displacement pump has no effect on theoperation of the administration equipment under gravity flow. However,with presently known apparatus, operation of the displacement pump tendsto cause a backfiow of the injection fluid into the drip observationchamber, located above the pump, so that the chamber becomes filled withfluid. When this occurs, it is no longer possible to observe the driprate, i.e., the rate at which the discrete droplets of fluid enter thecharm her from the supply container. This presents considerable problemsin actual practice, since observation of the drip rate is generally theonly means by which the attendant can determine whether fluid is flowingthrough the system, and at what rate.

Accordingly, one of the specific improved features of the presentinvention resides in the provision of an improved intravenousadministration equipment including, in series, a drip observationchamber and displacement pump, in which improved valve means areprovided in the pump to avoid backflow of fluid into the drip chamberduring operation of the pump, or at least to reduce backflow to such asubstantial extent that the level of fluid in the drip chamber is notmaterially increased. More speciflcally, the invention provides animproved check valve assembly, including valve and valve seat elementsof improved design, and improved means for supporting the valve element,whereby the valve is permitted to close more rapidly and moreeffectively, upon operation of the pump, than has been possibleheretofore. I

Another specific advantageous feature of the invention resides in theprovision of a displacement pump of novel and improved construction,which is less expensive to manufacture and more effective in operationthan similar apparatus of heretfore-k nown design. In this respect, theintravenous administration equipment of the type contemplated herein isintended for but a single use, after which it is discarded, and so mustbe of relatively economical design. At the same time, the structure mustbe extremely sturdy, and substantially percent foolproof, sincephysicians will entirely avoid the use of equipment which evenoccasionally fails during use.

formed and whereby a sturdy and non-separable mechanical pump structureis created. Specifically, the improved structure comprises novel endfittings for the flexible pump chamber, including novel couplingelements which cooperate with the check valve assemblies to secure theends of the pump chamber in the manner desired.

Another specific improved feature of the present invention resides inthe provision of an improved intravenous administration apparatus,including a drip observation chamber and a manually operabledisplacement pump, connected in series, wherein the drip chamber andpump form a compact, unitary assembly, providing for economicalmanufacture, packaging, storing, and shipping, and greatly facilitatingthe handling of the apparatus in use.

For a better understanding of the invention, and for a description ofadditional advantageous features thereof, reference should be made tothe following detailed specification and accompanying drawing, in which:

FIG. 1 is a front elevation, with parts broken away, of an intravenousadministration apparatus incorporating the features of the invention;

FIG. 2 is an enlarged elevational view, partly in section, illustratingfeatures of construction of the improved displacement pump assemblyincorporated in the apparatus of FIG. 1;

Below the drip observation chamber Ill is a pump assembly 14, whichreceives fluid from the chamber it) and delivers it, normally by gravityflow, into the upper end of a length of flexible tubing 15. The otherend of the tubing 15., which will be referred to as the lower end,

is connected to a short'length of surgical tubing 16, by

means of a suitable fitting 17, and the surgical tubing 16 is, in turn,connected to a hypodermic cannula 18, which may be of a conventionaltype adapted for insertion into the vein of a patient.

In general, the apparatus is placed in operation by inserting thetubular extension 11 through the bottle stopper 12 and suspending thebottle 13 upside-down, whereby the fluid therein flows into the dripobservation chamber by gravity. Conventionall an air cannula 19 isinserted through the stopper 12 and extends to a point near the bottomwall of the bottle 13 (top wall when the bottle is inverted) so that airmay flow into the bottle as fluid is drained therefrom.

Fluid entering the drip observation chamber 1%, through the tubularextension 11, passes through a drip tube 20, from which the fluid, inthe normal operation of the apparatus, falls in discrete droplets intothe chamber 10. The drip observation chamber 10 is formed in part by atransparent outer housing 21, through which the fall of droplets fromthe drip tube 20 may be observed, and in this way a physician or otherattendant may determine whether .the fluid is flowing properly from thebottle 13 and the approximate volumetric rate of flow.

Fluid within the drip observation chamber flows through a filteringscreen 22, of very finemesh, and into the upper end of the pumpassembly14, through an opening 23 in the upper end thereof. The pump 14 has acheck valve assembly 24 at its upper end, to be described in greaterdetail, which is normally open and therefore normally permits fluid toflow through the inlet opening 23. The lower end of the pump 14 also hasa check valve assembly 25, to be described in greater detail, which isalso normally open and permits the fluid within the pump to flow througha pump outlet opening into the tube 15.

At some point along the length of the flexible tube 15 is a conventionalvalve member 27, having a tapered slot (not specifically shown) therein,which is adapted to be moved transversely of the principal axis of thetube to constrict the interior passage thereof in varying degrees. Thearrangement is such that the valve member 27- may be employed to controlthe fiow of fluid through the flexible tubing 15, it being understood,in this respect, that the tubing sections 15, 16, and cannula 18 aredisposed below the outlet of the pump 14 during normal operation of theapparatus, so that fluid tends to flow to the tubinglS by gravity.

Fluid passing through the flexible tubing 15, beyond the valve member27, flows through the short length of surgical tubing 16 and into thehypodermic cannula 13 to be discharged into the vein of a patient. Thesurgical tubing 16 is provided primarily for the purpose of permittinghypodermic injections of additive substances into the stream of fluidflowing from the bottle 13, by projection of a needle through the sidewall of the tubing 6 16. The tubing 16, being self-sealing, will notleak fluid following withdrawal of a needle therefrom.

In normal operation, fluid draining from the bottle 15 will fill thesystem to a point somewhat below the lower end of-the drip tube 20, asindicated, by way of example only, at line 28. Accordingly, the pump 14is completely filled with fluid, as are the sections 15, 16 of thetubing,

while at the same time the level of'fluid is sufliciently below thelower end of the drip tube 20 to permit of the formation of individualdroplets of fluid at the end of the drip tube, so that the input offluid may be visually observed through the transparent drip housing 21.

As will be understood, the flow of injection fluid through theadministration apparatus, under the action of gravity alone, is quiteslow, this being a desirable feature under most conditions. However,under certain emergency conditions it is desirable to inject asubstantial quantity of fluid into the patient in a relatively shorttime. Accordingly, the pump 14, which is filled with fluid, may beactuated to force a certain quantity of the fluid at a rapid ratethrough the tubing 15, 16 and cannula 13. To this end, the pump includesa flexible outer casing 29 adapted to be deformed manually, as bysqueezing with the hand, whereupon the upper check valve assembly 24closes and fluid is forcibly displaced from the pump, through the loweroutlet thereof. The lower check valve assembly 25 prevents any returnflow of fluid into the interior of the pump when the casing 29 issubsequently allowed to expand, or when the fluid pressure in the lowerportion of the system for some other reason exceeds that in the pumpcasing.

One of the important considerations of the operation of the newintravenous administration apparatus is the prevention of the backflowoi fluid through the upper check valve assembly 24 during operation ofthe pump 1d. Thus, past experience has shown that there is a tendencyfor substantial quantities of fluid to escape through the upper checkvalve when the pump 14 is initially brought into operation. Suchbackflow of fluid may raise the fluid level 28 in the drip observationchamber 19 up to the lower end of the drip tubefifl, or so near theretoas to prevent the formation of individual droplets, so that it isimpossible to determine either the rate of flow of the fluid or whetheror not it is flowing at all. This, of course, is intolerable and stepsmust be taken to lower the fluid level, as by removing the cannula 18 totemporarily increase the rate of flow of fluid.

Another important consideration, in respect of intravenousadministration apparatus of the type herein described, is the provisionof an economical, compact, and wholly dependable mechanical assemblywhich may be quickly brought into operation and efliciently utilized forthe purpose intended. The new apparatus incorporates many specificfeatures, to be presently described, which jointly provide substantialimprovements in the structure and operation of the new apparatus.

Referring now to FIG. 2, the upper check valve assembly 24 comprises amulti-purpose fitting 3b, which is advantageously molded from plasticmaterial, such as clear polystyrene. The upper valve fitting St? has abase flange portion 31 forming, in ettect, the upper wall of thefitting, in which there are provided upwardly opening concentricrecesses 32, 33, as wellas a central opening 23, forming an inlet intothe pump. The inner one of the concentric grooves is adapted to receivethe lower end of the filter screen 22, the screen being of generallycylindrical form, closed at its upper end. The outer groove 32 receivesthe lower end of the drip observation housing 21, which is alsoadvantageously formed of clear polystyrene material, the housing 21being of generally cylindrical cross-section and having a reduced upperportion from which project the tubular extension 11 and drip tube 20, asintegral parts of the housing. In the assembled apparatus, theobservation housing 21 and filter screen 22 are cemented or otherwisesecured in the respective concentric grooves 32, 33, whereby to berigidly connected to the valve fitting 3t In accordance with theinvention, the upper valve fitting 3b is provided interiorly with anaxial recess 34, into which projects an annular flange 35, defining the.inlet opening 23 and having a frusto-conical lower surface 36 forming avalve seat. As shown in FIG. 2, the

axial flange 35 projects below the upper end of the annular recess 34,as defined by the base flange 31, a substantial distance, which may bein the order'of oneeighth inch, in a fitting having an overalldiameterin the order of 1 inches. Accordingly, the flange 35, togetherwith the depending outer cylindrical wall 37 of the valve fitting 3t),defines an annular pocket 38, which forms an important part of theinvention. The pocket 38, as will be described in connection with theoperation of the valve assembly 26, serves to trap air which wouldotherwise interfere with the proper operation of the valve.

At the lower end of the wall 37 of the upper valve fitting is mounted avalve guide member 39, formed of plastic material, such as clearpolystyrene, which comprises a vertically disposed cylindrical guidesleeve 40, suspended in coaxial relation to the valve fitting 30 bymeans of integral diametrically disposed supports 41 (FIG. 3). At theends of the supports 41 are integral arcuate flanges 42, receivedagainst the lower end of the valve fitting wall 37 and cemented rigidlythereto. In accordance with one aspect of the invention, the guidesupports 41 are of narrow transverse dimension and are provided withpointed upper surfaces, as indicated in FIGS. 1 and 2. The arrangementis such that fluid may flow downward, through the valve assembly,Without the occurrence of substantial bubble formations on the guidesupports.

Loosely received in the cylindrical guide sleeve 40 is the stem 43 of avalve plunger 44. Advantageously,

the head portion 45 of the valve plunger is of hemispherical shape,giving the plunger a mushroom-like appearance. The plunger 44 isadvantageously formed of relatively soft surgical rubber material,having a specific gravity somewhat less than the injection fluid to beadministered with the apparatus. The arrangement is such that, when thepump chamber is filled with fluid, the valve plunger 44 will tend tofloat in the fluid and be urged toward its closed position, against thefrusto-conical valve seat 36. The head of the fluid is great enough,however, to hold the plunger open sufliciently to permit a propergravity flow of fluid, as will be understood.

The lower valve assembly 25, in the illustrated form of the invention,includes a valve fitting 46, formed of material such as clearpolystyrene, and having a bottom wall 47 and an upwardly extendingcylindrical outer Wall 48. The walls 47, 48 form a cylindrical recess,into which projects an integral, generally cylindrical, valve guide 49.The guide 49, in effect, forms an extension of a tubular outlet 50,leading downward from the body of the fitting 46, and has a plurality ofvertical slots 51 (FIG. 4) therein providing for the relatively freeflow of fluid into the outlet 50.

As shown in FIG. 2, the valve guide 49 loosely receives the stem portionof a valve plunger 52, the plungor being substantially the same as theplunger 44 of the upper valve assembly. The upper end of the valve guide49 forms an abutment surface, against which the head of the valveplunger 52' may rest. However, as will be understood, in the normaloperation of the apparatus, under gravity flow conditions, the valveplunger 52 will tend to float in the surrounding fluid. Y

Received at the top of the lower valve fitting 46 is a cap 53, formed ofmaterial such as clear polystyrene and having radially and axiallyextending flanges adapted to snugly engage the end surface and innersurface of the cylindrical wall 48, and to be cemented thereto. The cap53 has a central opening 54 therein, forming an outlet from the pumpchamber, and has a frusto-conical valve seat 55 facing downward,directly above the valve plunger 52.

In the illustrated form of the invention, the valve cap 53 has anannular recess or pocket 56 surrounding the valve seat 55, which may beeffective in trapping air bubbles formed about the valve seat. However,as will be come apparent subsequently, the lower valve assembly does notform a critical part of the injection apparatus, as

is not an important consideration; in fact, in some cases, the lowervalve assembly may be omitted altogether.

Extending between the upper and lower valve assemblies is the normallycylindrical pump casing 29, which is relatively flexible, being formedof a suitable plastic material such as plasticized polyvinyl chloride.In accordance with the invention, the 'ends of the pump casing 29 arereceived over the cylindrical walls 37, 48 of the valve fittings 30, 46,the said walls having tapered outer surfaces and being of somewhatlarger diameter, at least at the base, than the inside diameter of thecasing. In order to secure the casing ends tightly to the fittings 30,46, a pair of tube clamps 57, 58 of improved design are provided, whichgrip the casing 29 adjacent its ends, firmly retaining the casing insealed relation to the fitting 3G, 46, and which lockingly engageportions of the valve fittings to form a rigid and durable mechanicalstructure.

The fittings 57, 58 are in the form of collars, having openings 59therein of approximately the same diameter as the pump casing 29. Theinner walls of the openings 59 advantageously have sharp grippingshoulders 60,.61 (lower FIG. 2) which, in the assembled apparatus, areembedded in the casing wall to lockingly grip the latter.

Each clamping collar has a generally cylindrical outer wall 62, ofgreater diameter than the pump casing 29, which has a plurality ofintegral locking fingers 63 spaced circumferentially thereabout. Thelocking fingers 63 have beveled end faces 64, and locking shoulders 65are adapted to engage flanges 66 on the respective valve fittings 36,46. As indicated in FIG. 2, the flanges 66 have beveled faces 67 adaptedto engage the beveled faces 64 of the locking fingers, upon axialapplication of the locking collars to the valve fittings, whereby thelocking fingers are forced outwardly over the flanges 66 and intolocking engagement therewith.

In the assembly of the pump casing and valves, the locking collars 57,58 are slipped over the casing 29, after which the ends of the casingare applied over the tapered outer walls of the valve fittings 30, 46.The end portions of the casing are flared outwardly somewhat by thetapered outer surfaces of the fitting walls 37, 48, so that a relativelytight connection is afforded. The locking collars 57, 58 are thenapplied to the respective valve fittings 36, 46, so that the fingers 63are lockingly engaged with the flanges 66 thereof.

As will be observed in FIGS. 1 and 2, the diameter of the centralopenings 59 in the locking collars is such that, when the collars areapplied to the valve fittings, the annular space between the fittingsand the openings is less than the Wall thickness of the pump casing 29.Accordingly, the walls of the casing are deformed, and a cold flow ofthe plastic casing material takes place, so that the casing is, for allpractical purposes, mechanically locked together with the fittings andcollars.

In the operation of the new administration apparatus, fluid flows fromthe bottle 13, through the drip observation chamber 10, pump 14 andtubing 15, into the vein of a patient. The pump valves are normallyopen, although the valve plungers 44, 52 tend to float in the fluid andtherefore tend to seat against their respective valve seating surfaces.Under normal conditions, the level of the fluid is such that the dripobservation chamber 10 is partly filled, although not to such an extentthat the fluid level is close to the drip tube, and the inflow of fluidmay be observed in the form of discrete droplets falling from the driptube 20.

If it becomes necessary to force fluid through the apparatus at anincreased rate, the flexible pump casing 29 is compressed manually, asindicated in FIG. 2, to displace a portion of fluid therein. When thepump is actuated, the valve element 44 of the upper valve assembly 24immediately seals tightly against the valve surface 36, preventingbackflow of fluid into the drip observation chamber 10, and the fluid isforced out through the bottom valve assembly 25. The lower valve element52 is, of course, forced downwardly by the force of thedownwardly'fiowing fluid.

Advantageously, the size of the pump chamber 29 is such that when it issqueezed to a collapsed condition, by a hand of average size,approximately twenty-five cubic centimeters of injection fluid will bedisplaced therefrom. This may be accomplished by so dimensioning thecasing 29 that the effective portion has a volume in the order of 32-35cc.

After the pump casing has been manually collapsed, to effect a forced.injection of fiuid, it is released and permitted, by reason of itsinherent resiliency, to return to its normal cylindrical condition. Thiscauses the lower valve assembly 25 to close, and fluid again flows intothe pump chamber through the upper valve assembly 24.

One of the most important aspects of the invention resides in thestructure of the upper valve assembly 24, particularly in respect of theprovision therein of the annular air pocket 38' surrounding andgenerally above the valve seat 36. In the normal operation of apparatusof the type herein concerned, minute bubbles of air tend to adhere tothe valve seating surface 36' and surrounding surfaces. As a result,when the pump 14 is actuated, in-

stantaneous closing of the valve plunger 44 is prevented, and anexcessive quantity of the injection fluid flows upwardly from the pumpchamber, into the drip observa* 'tion chamber. As mentioned previously,this often causes an intolerable condition, in that the drip observationchamber becomes filled, by the back-flowing fiuid and further flowobservation is rendered impossible. This condition is satisfactorilyremedied in accordance with the present invention, by providing theannular air pocket 38 above the valve seating surface 36, which trapsair' bubble formations formed in the valving area and therebyefiectively prevents the undesirable accumulation of bubbles on thevalving surfaces.

Another important feature of the invention resides in the provision ofan improved valve assembly, for intravenous administration equipment, inwhich the support or guide for the valve plunger is of a novel andimproved design. Thus, in the upper valve assembly 24, the valve guide39 comprises supports 41 of minimum cross-section and having pointedupper surfaces. The arrangement is such that air bubble formations onand about the supports 41 are avoided, and the consequent interferencewith proper valve operation is eliminated. The structure of the valveguide 39 is also advantageous in that it may be inexpensivelymanufactured and easily assembled into the complete valve assembly.

Another important aspect of the invention resides in the provision of anintravenous administration apparatus of the type described, whichincorporates novel and improved structural features providing for easieraseembly and resulting in a compact, unitary and highly rugged assemblywhich is adapted for eflicient handling and use.

To this end, the new apparatus includes improved com 1 binationfittings, by means of which the series-related drip observation chamberand pump chamber are mechanically interconnected as a single unitarystructure. In addition, the new apparatus incorporates improved meansfor securing the opposite ends of the flexible pump casing to therespective valve assemblies, whereby to aflord a rigid, sealed,mechanical connection. The arrangement is such that assembly of theapparatus may be carried out expeditiously, without special skills, anda highly satisfactory structure is afforded.

It should be understood, however, that the specific form of the newapparatus herein illustrated and described is intended to berepresentative only, as certain. changes maybe made therein withoutdeparting from the clear teachings of the invention. Reference shouldtherefore be made to the following appended claims in determin ingtnefull scope of the invention. Y

8 I'claim:

1. An intravenous administration apparatus of the type adapted. toprovide a continuous channel for injection fiuid flowing from a sourceof supply to a hypodermic cannula comprising, in combination, a dripobservation chamber, a pump below the chamber, channel forming meansconnecting said pump and chamber in series relation, said channelforming means including a check valve located below said chamber andabove said pump, said check valve comprising a valve fitting having anupper wall and depending side walls forming a downwardly opening valvechamber, said upper wall having an openiug therein forming an inlet, avalve seat surrounding said inlet and exposed to said valve chamber,said fitting having an annular recess therein surrounding said valveseat and located above said seat forming an air pocket, and a valveelement movably supported below said valve seat and adapted for movementinto sealing relation with said valve seat and formed of a material ofless density than the injection fluid.

2. The intravenous administration apparatus of claim 1, in which theinlet opening of said valve fitting is defined, at least in part, by anannular flange projecting downwardly from said upper wall, said airpocket being defined in part by said annular flange.

3. The intravenous administration apparatus of claim 1', in which saidvalve seat is an annular frusto-conical surface disposed at an angle ofin the order of 45 with respect to the axis of said fitting, and saidvalve element has an active valving portion of spherical contour.

4. The intravenous administration apparatus of claim 1 in which thevalve element is a valve plunger of rnushroom-like shape having anenlarged active valving portion and a slender elongated guide portion,and which includes a valve guide member, said guide member having asleeve-like portion adapted to receive and guide the guide portion ofsaid valve plunger, said guide member further having a pair of integraldiametrically disposed supports secured to the depending side walls ofsaid valve fitting and supporting said sleeve-like member in coaxialrelation thereto, said supports having pointed upper surfaces to preventthe formation of air bubbles thcreabout.

5. The intravenous administration apparatus of claim 1, in which saidvalve fitting has means at its upper end for securing a portion of saiddrip observation chamber, said chamber being formed in part by saidupper wall, and said valve fitting further having means at its lower endfor securing a portion of said pump, said pump being formed in part bysaid upper wall.

6. In an intravenous administration apparatus of the type adapted toprovide a continuous channel for injection fluid flowing from a sourceof supply to a hypodermic cannula and including a drip observationchamber, a pump below the chamber and connected in series relationtherewith, and a check valve between the pump and chamber, theimprovement characterized by said valve comprising a fitting formed ofrigid plastic material, said drip observation chamber comprising ahousing formed of plastic material and secured rigidly to said valvefitting, said chamber being formed in part by said fitting, and saidpump comprising a tubular section of deformable plastic material, saidsection being rigidly secured at one end to said fitting, said pumpbeing formed in part by said fitting.

7. The intravenous administration apparatus of claim 6, in which thedepending walls of said fitting are tapered and of smaller outsidediameter at the bottom, said section of deformable plastic materialbeing generally cylindrical in form and having an inside diameter lessthan the large-diameter portion of the tapered walls of said fitting,said sectionbeing adapted to be secured in rigid and fluid-tightrelation to said fitting upon axial application of said section oversaid tapered walls.

1 8. The intravenous administration apparatus of claim 7, which includesa locking collar adapted to be received over said tubular section andsaid tapered walls and to be lockingly engaged with said fitting, saidcollar having an opening therein of a diameter not substantially greaterthan the outside diameter of said tubular section, whereby upon axialapplication of said collar over the assembled section and tapered wallssaid tubular section is deformed and gripped by said collar.

9. The intravenous administration apparatus of claim 8, in which saidlocking collar has an internal shoulder adapted to contact said tubularsection upon axial application of the collar over the assembled tubularsection and tapered walls, said deformable plastic material beingadapted to cold flow under continued pressure whereby portions of saidmaterial flow behind said shoulder to mechanically interlock saidtubular section with said collar.

10. The intravenous administration apparatus of claim 6, in which saiddrip observation housing has a generally cylindrical base portion, saiddrip observation chamber includes a filtering screen having a generallycylindrical base portion of smaller diameter than the base portion ofsaid housing, said fitting having concentric annular grooves in itsupper wall adapted to receive the respective base portions of saidhousing and filter screen.

References (Iited in the file of this patent UNITED STATES PATENTS812,451 Rice Feb. 13, 1906 1,324,674 Johnson Dec. 9, 1919 2,394,632Parker Feb. 12, 1946 2,603,493 Rusconi July 15, 1952 2,681,654 Ryan etal. June 22, 1954

